The goal of this research is to elucidate the regulatory mechanisms involved in the control of biodegradative threonine dehydratase of Escherichia coli and Salmonella typhimurium, a prototypic allosteric enzyme implicated in the anaerobic energy metabolism. Using biochemical techniques we are examining the structural organization and the catalytic efficiency of this enzyme when they interact with cellular metabolites. Specifically, we are interested in the covalent binding sites of pyruvate and gloyoxylate, and a comparison of the amino acid sequence of the two "covalent-site" peptides of the dehydratase from E. coli and Salmonella. A separate aspect of the work involves isolation and characterization of mutants that have lesions in both the structural gene of the protein and in various regulatory loci to understand the mechanism of enzyme induction in vivo.